As a curing agent exhibiting low-temperature rapid-curing activity for an epoxy resin, an aluminum chelate-based latent curing agent in which an aluminum chelate-based curing agent is held in a porous resin particle obtained by subjecting a polyfunctional isocyanate compound to interfacial polymerization and subjecting a radical polymerizable compound to radical polymerization at the same time has been proposed (Patent Document 1).